1. Field of the Invention
This invention relates to the field of suspensions for disk drives. More particularly, this invention relates to the field of a ring gimbal suspension having low stiffness and low circuit contribution to stiffness.
2. Description of Related Art
Magnetic hard disk drives and other types of spinning media drives such as optical disk drives are well known. FIG. 1 illustrates a typical prior art hard disk drive and suspension for which the present invention is applicable. Disk drive unit 10 includes a spinning magnetic disk 12 containing a pattern of magnetic ones and zeroes on it that constitutes the data stored on the disk drive. Disk drive unit 10 further includes a disk drive suspension 14 to which a magnetic head slider (not shown) is mounted. Suspension 14 is coupled to an actuator arm 16, which in turn is coupled to a voice coil motor (not shown) that moves the suspension 14 in order to position it over the correct data track on disk 12. The magnetic head slider is carried on a gimbal which allows the slider to pitch and roll so that the slider follows the data track on the disk, and allows for vibrations of the disk, inertial events such as bumping, and irregularities in the disk's surface.
Various suspension designs have been proposed and used throughout the years. One type of suspension is a ring gimbal suspension. U.S. Patent Publication No. US2009/0268347 by Muraki et al. discloses a ring gimbal design that is intended to produce low pitch and roll stiffness. Generally speaking, low pitch and roll stiffness are desired in a suspension gimbal so that the head slider can pitch and roll as freely as possible as the disk surface spins underneath the slider.
One of the steps in the manufacturing process of a suspension is the pitch static attitude (PSA) adjustment step. The PSA is adjusted by bending plastically deformable part(s) of the suspension so that the pitch and roll angles of the slider, and the gram force with which the slider presses down onto the magnetic disk surface, are correct in the non-spinning state (static state) of the disk drive. The PSA adjustment process can include placing slight, permanent bends in the stainless steel portions of both the suspension spring portion and/or the gimbal.